The earth’s hard coal will last until the year 2050 or 2100.

John Elfreth Watkins : engineer
Man will have found electricity manufactured by water-power to be much cheaper. Every river or creek with any suitable fall will be equippid with water-motors, turnbing dynamos, making electricity.

Tom Geoghegan. "Ten 100-year predictions that came true", BBC News Magazine. 11 Jan 2012.